1. Field of the Invention
The present invention relates generally to an optical recording medium and a manufacturing method thereof, and more particularly to a user recordable optical recording medium and a manufacturing method thereof wherein unauthorized recording and reproduction of information data is disabled.
2. Description of the Related Art
At present, a write-once DVD-R (Digital Versatile Disc-Recordable) has been commercially produced as a user recordable optical recording medium having a recording capacity of several gigabytes (Gbytes), and a rewritable DVD-RW (DVD-Rewritable) is under development. In addition, a large amount of high quality copies can be made without substantial degradation with the significantly improved performance of such large capacity digital optical recording media and recording/reproducing apparatus.
FIG. 1 is a diagram showing a layout of a physical sector in a radial direction of a recording surface on a DVD-RW which is taken as an example. An information area for recording information data is made up of a lead-in area, a data area, and a lead-out area in this order from the starting point of the information area (i.e., starting point of the physical area) outwardly in the radial direction.
As shown in FIG. 2, the lead-in area contains data for use in reproducing the disc such as a reference code, control data, and so on. A control data region is comprised of 192 ECC (Error Correction Code) blocks. In FIG. 2, ECC blocks within the control data region are indicated using relative sector numbers in a range of 0 to 15. Each of the ECC blocks has the same contents. In other words, 192 ECC blocks having the same contents are recorded in succession. One ECC block is comprised of 16 sectors in which recorded are physical format information, disc manufacturing information, and contents provider information. Thus, data related to the reproduction of such information data is recorded in the control data region in the lead-in area upon recording information data on the disc. Upon reproduction of the disc, a reproducing apparatus reads these data to reproduce recorded information data such as video data based on the read information. In this way, the disc is recorded and reproduced.
However, with the ability of readily providing a large amount of high quality copies as mentioned above, there has arisen a serious problem in the development of the copy protection technology for preventing unauthorized or illegal copies of recorded information data such as video and audio data, computer programs, and so on.
The present invention has been made in view of the problem mentioned above, and the object of the invention is to provide an optical recording medium and a manufacturing method thereof wherein unauthorized recording and reproduction of information data is disabled.
To achieve the object, according to one aspect of the present invention, there is provided an optical recording medium having an information data recording region including groove tracks and land tracks formed in alternation, each of the groove tracks carrying thereon a sequence of alternately appearing mark portions and space portions, the sequence representing an information data signal, and the land tracks being formed with a prepit train including at least one prepit which carries pre-information every predetermined data unit of the groove tracks, wherein at least a portion of the groove tracks comprises a plurality of groove portions separated by groove-absent portions in a rotational direction of the optical recording medium, each of the mark portions or each of the space portions includes one of the groove-absent portions.
According to another aspect of the present invention, there is provided an optical recording medium having an information data recording region including groove tracks and land tracks formed in alternation, each of the groove tracks carrying thereon a sequence of alternately appearing mark portions and space portions, the sequence representing an information data signal, and the land tracks being formed with a prepit train including at least one prepit which carries pre-information every predetermined data unit of the groove tracks, wherein at least a portion of the groove tracks comprises a plurality of groove portions separated by groove-absent portions in a rotational direction of the optical recording medium, each of the mark portions or each of the space portions includes one of the groove-absent portions, and at least one of two groove tracks adjacent to the prepit train has a continuous groove portion extending at least from a leading end to a trailing end of at least one prepit included in the prepit train in a rotational direction of the optical recording medium. According to another aspect of the present invention, there is provided an optical recording medium having an information data recording region including groove tracks and land tracks formed in alternation, each of the groove tracks carrying thereon a sequence of alternately appearing mark portions and space portions, the sequence representing an information data signal, and the land tracks being formed with a prepit train including at least one prepit which carries pre-information every predetermined data unit of the groove tracks, wherein at least a portion of the groove tracks comprises a plurality of groove portions separated by groove-absent portions in a rotational direction of the optical recording medium, each of the mark portions or each of the space portions includes one of the groove-absent portions, and at least one of two groove tracks adjacent to the prepit train has a continuous groove-absent portion extending at least from a leading end to a trailing end of at least one prepit included in the prepit train in a rotational direction of the optical recording medium.
According to another aspect of the present invention, there is provided an optical recording medium having an information data recording region including groove tracks and land tracks formed in alternation, each of the groove tracks carrying thereon a sequence of alternately appearing mark portions and space portions, the sequence representing an information data signal, and the land tracks being formed with a prepit train including at least one prepit which carries pre-information every predetermined data unit of the groove tracks, wherein at least a portion of the groove tracks comprises a plurality of groove portions separated by groove-absent portions in a rotational direction of the optical recording medium, each of the mark portions or each of the space portions includes one of the groove-absent portions, one of two groove tracks adjacent to the prepit train has a continuous groove portion extending at least from a leading end to a trailing end of at least one prepit included in the prepit train in a rotational direction of the optical recording medium, and another groove track of the two groove tracks adjacent to the prepit train has a continuous groove-absent portion extending at least from a leading end to a trailing end of at least one prepit included in the prepit train in a rotational direction of the optical recording medium.
According to further another aspect of the present invention, there is provided a method of manufacturing an optical recording medium having an information data recording region, comprising the steps of forming groove tracks carrying thereon a sequence of alternately appearing mark portions and space portions, the sequence representing an information data signal, and forming land tracks, in alternation with the groove tracks, having a prepit train including at least one prepit which carries pre-information every predetermined data unit of the groove tracks, wherein the step of forming groove tracks includes a step of forming a plurality of groove portions, at least in a portion of the groove tracks, separated by groove-absent portions in a rotational direction of the optical recording medium, each of the mark portions or each of the space portions includes one of the groove-absent portions.
According to another aspect of the present invention, there is provided a method of manufacturing an optical recording medium having an information data recording region, comprising the steps of forming groove tracks carrying thereon a sequence of alternately appearing mark portions and space portions, the sequence representing an information data signal, and forming land tracks, in alternation with the groove tracks, having a prepit train including at least one prepit which carries pre-information every predetermined data unit of the groove tracks, wherein the step of forming groove tracks includes a step of forming a plurality of groove portions, at least in a portion of the groove tracks, separated by groove-absent portions in a rotational direction of the optical recording medium, each of the mark portions or each of the space portions includes one of the groove-absent portions, and at least one of two groove tracks adjacent to the prepit train has a continuous groove portion extending at least from a leading end to a trailing end of at least one prepit included in the prepit train in a rotational direction of the optical recording medium.
According to further another aspect of the present invention, there is provided a method of manufacturing an optical recording medium having an information data recording region, comprising the steps of forming groove tracks carrying thereon a sequence of alternately appearing mark portions and space portions, the sequence representing an information data signal, and forming land tracks, in alternation with the groove tracks, having a prepit train including at least one prepit which carries pre-information every predetermined data unit of the groove tracks, wherein the step of forming groove tracks includes a step of forming a plurality of groove portions, at least in a portion of the groove tracks, separated by groove-absent portions in a rotational direction of the optical recording medium, each of the mark portions or each of the space portions includes one of the groove-absent portions, and at least one of two groove tracks adjacent to the prepit train has a continuous groove-absent portion extending at least from a leading end to a trailing end of at least one prepit included in the prepit train in a rotational direction of the optical recording medium.